[SCSI] fcoe: drop FCoE LOGO in FIP mode

Allowing FCoE LOGO followed by CVL in this case prevents
FIP login back to the FCF and then keeps lport offline,
only FIP LOGO and CLV needs to be processed while in
FIP mode, therefore this patch drops FCoE LOGO in FIP mode.

Added fcoe_filter_frames() to filter out above mentioned LOGO
in fcoe rx path along with other existing filtering in code
for bad CRC frames. Adding separate fcoe_filter_frames function
helped with better code indentations and if needed then same
will allow adding more filters at one place in future.

This LOGO drop is added after FCP frames passed up to avoid
any additional checks on fast path for this.

Signed-off-by: Vasu Dev <vasu.dev@intel.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>